Once inside Grand Duke Henri gave a heart-felt speech to his son and new daughter-in-law saying he and his wife, Maria Teresa are "happy and proud" that the couple are "embarking on this journey together through life."

Also gracing the palace with their royal presence were Princess Caroline of Monaco, Princess Marie-Chantal of Greece and British-born Princess Claire of Belgium.

Not wanting to be outdone by the gala's female attendees, Guillaume's three brothers Felix, Louis and Sebastien were handsomely attired in black tuxedos.